It is conventionally known that an illuminated push-button switch of which a surface or a key top is illuminated is used for a key of a push phone device and a keyboard.
As illustrated in FIG. 18, for example, an illuminated push-button switch 100 provided in a phone device disclosed in Patent Document 1 includes a key-pad member 110 having a light guiding part 111 that allows the light emitted from an LED 101 to pass therethrough, and a push-button member 120 that covers from a light exit surface 111a of the light guiding part 111 formed in the center of the key-pad member 110 to a portion of an outer wall surface 112 of the key-pad member 110.
In the illuminated push-button switch 100, the light emitted from the LED 101 is guided through the light guiding part 111 to a touch surface 121 of the push-button member 120. Thus, the emitted light concentrates at a portion of the touch surface 121 of the push-button member 120, and the luminescence at this portion increases. As a result, the visibility of the touch surface 121 improves.
In another configuration, as illustrated in FIGS. 19(a) and 19(b), for example, a keyboard switch 200 disclosed in Patent Document 2 includes a key-cap 210, a casing 201, a push-button member 220 slidable to the lower side and including a cylindrical member 221 that protrudes from an opening 201a of the casing 201, and an LED 202 provided in the center of the push-button member 220. As illustrated in FIG. 19(c), a cylindrical part 211 formed on the back side of the key-cap 210 fits onto the cylindrical member 221 of the push-button member 220.
The illuminated push-button switch 100 disclosed in Patent Document 1 and the keyboard switch 200 disclosed in Patent Document 2 each have an upper-surface area of the push-button member 120 or the key-cap 210, which is the key top, larger than the area of the button, which is the key-pad member 110 or the push-button member 220.